1. Field of the Invention
The present invention relates to an ink jet printer, and, more particularly, to a maintenance or service station for an ink jet printer.
2. Description of the Related Art
Current ink jet printhead technology fires very tiny ink droplets in order to provide the best print quality. The ink droplets are so small that if they do not impact a surface within a short distance of leaving the nozzles, they tend to drift away in a cloud of mist. During printing, this is not an issue because the paper is only about 1.00 mm to 1.25 mm away. However during the spitting performed in a maintenance cycle, there is a much greater distance to cover before the ink reaches the features designed to receive them on the maintenance sled. In this empty space, an ink mist cloud can form and float into other areas of the printer. Over time, this ink misting collects on the inside of the covers, some even escaping through holes in the covers to form splotches on the inside of the covers.
It is known to attach a rotating drum 20 (FIG. 1) to a sled 22 in order to give the ink a place to collect. The drum turns so that the ink drips off into the ink well and a clean surface is positioned for the next spit. It is also possible to disable the mechanism for the drum rotation, and to allow the ink to drip around the sides as it collects on the top. It is also possible to place a drum 24 (FIG. 2) between a printhead cap 26 and a printhead wiper 28 on a sled 30. Drum 24 provides a curved surface, concave down, that the ink strikes and then runs off, to be collected beneath the drum for evaporative dispersion.
It is also known to provide the maintenance sled with a chimney into which the spit ink can be directed. The chimney is intended to surround the ink mist cloud and thereby prevent its movement into other areas of the printer. The ink mist collects on the inside walls of the chimney and flows down toward an ink collection area underneath the sled. Known chimneys are affixed to the sled, as are rotating and stationary drums. The chimney and drum must be designed such that, as the sled moves upward, the top of the chimney or drum does not physically contact or otherwise interfere with the printhead. Thus, the top of the chimney or drum must be maintained at a distance during the spitting of the printhead that is equal to the vertical distance the sled travels before other maintenance functions are performed, such as capping. This is illustrated in FIG. 3, wherein a gap 32 between a chimney 34 and a printhead 36 is maintained during the spitting operation so that chimney 34 does not interfere with printhead 36 during the capping operation (FIG. 4). A problem with this implementation of the chimney or drum is that with this rather large gap, the mist cloud is not completely captured in the chimney or collected by the drum, and can escape the maintenance area.
What is needed in the art is a device for preventing the drifting of a cloud of ink mist after a spitting operation in a maintenance station.